From: wneumann@...
Date: 2006-08-04T03:45:07+09:00
Subject: Re: For performance, write it in OCaml

Jon Harrop wrote:

> Here's my OCaml2 (based upon William's):

Just a small note here:
Depending on your goals, you can do even better by stuffing the output
in a buffer then dumping the buffer at the end of computation (see
example code below).  Of course this consumes more memory, and isn't
possible on a larger board, but it's yet another tweak to exploit,
since we're benchmarking output in addition to benchmarking work (note
that on my G5 output to stdout is a bit slower than your version, but
this isn't the case on the AMD machines I have access to -- redirecting
to a file is always faster).

let rec add_a_row row =
  let buf = Buffer.create 1_000_000 in
  let rec addh row =
    match row with
    | x when x=size ->
      for i=0 to size-1 do
        String.blit output_strings.(board.(i)) 0 op (i*(size+1)) size
      done;
      Buffer.add_string buf op; Buffer.add_char buf '\n'
    | _ ->
      for latest = 0 to n - 1 do
        let prev_row = ref 0 in
        let incompat = incompat.(latest) in
        while !prev_row < row && not incompat.(board.(!prev_row)) do
          incr prev_row
        done;
        if !prev_row = row then (board.(row) <- latest; addh (row + 1))
      done in
  addh row;
  Buffer.output_buffer stdout buf

let () = 
  add_a_row 0;